


A Siren's Tail

by 69inthebackofa67 (Zephyreon)



Category: Supernatural
Genre: Hurt Dean Winchester, Hurt/Comfort, M/M, Marine Biologist!Cas, Pregnant Dean, Siren!Azazel, Siren!Lucifer, Smuggler!Alistair, siren au, siren!Dean, siren!Sam
Language: English
Status: In-Progress
Published: 2015-12-04
Updated: 2016-01-29
Packaged: 2018-05-04 23:19:30
Rating: Mature
Warnings: Graphic Depictions Of Violence, Rape/Non-Con
Chapters: 6
Words: 11,266
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5352140
Author URL: https://archiveofourown.org/users/Zephyreon/pseuds/69inthebackofa67
Summary: <blockquote class="userstuff">
              <p>!!!WARNING: I KNOW NOT HOW TO SUMMARY</p><p>Basically, Cas rescues Siren!Dean from Alistair, who then meets Siren!Sam, and the two turn out to be mates.</p><p>WARNING OVER</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> If you've read this before, then it's back and hopefully wont' be going anywhere anytime soon!

Castiel got the call an hour after he saw the news report. Alistair Milton was known far and wide as one of the world’s premiere smugglers of goods, both material and alive. Several agencies, the FBI, CIA,  and some official-sounding acronyms Castiel had never heard of, were all on his ass but could never get any charges to stick. That was until they’d found one of his live storage warehouses.

Castiel Novak was one of the best marine biologists around, so when SWAT found rows and rows of aquariums, they thought to call him. It was about two hours from aquarium-rescue center he headed, but Cas made it there in under one after they’d told him that there was a siren there.

How Alistair had gotten his hands on one of the rarest creatures on the planet, Cas didn’t know, but it wasn’t important. What was was getting to it in time.

Cas pulled the rescue center’s van up in front of the warehouse, and was met by a detective with dark hair.

“You here about the siren?” he asked and Cas nodded. “Follow me, then.”

He led Castiel to the very back of the warehouse to a tank barely big enough for Cas’ brother Gabriel, let alone the siren that was currently in it. The siren had doubled up on himself in order to fit and also to protect the tiny bump of a belly he was sporting.

Cas’ concern for him ratcheted up several notches when he saw the poor thing was gravid, since Alistair probably had never taken proper care of him. Cas knew he needed a thorough exam, but that had to wait until they could get him out.

“Gabriel! Get the stretcher back here!” Cas called over his shoulder. The siren flinched at the loud noise and pulled harder at the cuff clamped around the end of his emerald green tail. The chain wasn’t giving any more slack, so he only succeeded in aggravating the already irritated flesh more.

Someone had to track down the key to the lock keeping the tank lid in place, and Castiel took a minute to look over the siren. He was thin as a rail, clearly emaciated, and his skin had an unhealthy pallor that made his freckles stand out all the more. His eyes and tail were the same vivid spectrum of greens, and he had a short shock of gold-blonde hair. Had he been healthy, he would have been beautiful.

A pair of bolt cutters were pressed into Cas’ hands and the siren started thrashing when the top of his tank was taken off. He couldn’t do much, since his tail was chained to one end and the metal collar around his neck to the other, but Cas was afraid he was going to hurt himself. To make things worse, Cas couldn’t give him one of the sedatives in his bag without harming the egg inside the siren, and the kind that wouldn’t were back in the van. There was the off chance it wasn’t fertilized and there wasn’t anything to harm, but Cas wasn’t willing to risk it.

The siren quieted down, though, when he saw the bolt cutters Castiel was wielding and allowed him to snip through the chains holding him in place. He only gave Cas a little trouble when he manhandled him out of the tank and onto the stretcher, but flipped out when Gabriel’s hand strayed near his stomach.

As a result, Gabriel wouldn’t carry the end of the stretcher near the siren’s tail and jumped at Cas’ request to drive the van. Once settled in the back, Cas covered the siren in wet towels to keep him moist. He was careful to keep his hands away from the siren’s belly, at least until he could get him back to the center, and instead busied himself with getting the metal cuffs off. They hadn’t been made to withstand long periods in the water, and had rusted badly, meaning Cas could just use force and break them open.

He didn’t even have to try that hard, which was another indicator that the siren had been severely neglected. Sirens were stronger than humans, so had he been healthy, he shouldn’t have had any problem breaking the cuffs.

“I’m sorry, this will sting.” Cas said as he doused a rag in disinfectant. The siren nodded and bit down on his bottom lip. He only flinched a little as Cas cleaned out the wounds, and didn’t move at all as he applied a thick antibiotic cream. Cas finished by wrapping his wrists, neck, and the end of his tail in waterproof bandages, and realized he’d never gotten the siren’s name or given his own.

“I’m Castiel, but you can call me Cas. Do you have a name?” Cas asked. The siren pondered it for a moment and nodded, but didn’t say anything.

“Are you going to tell me?” A sad shake of the head, and the siren’s green eyes wouldn’t meet Castiel’s blue. Tears started welling up in his eyes and Cas rushed to comfort him. “Hey, it’s okay, we’ll figure something out. For now we’ll just stick to yes/no questions, alright?” Cas got a shaky nod in response and counted it as a win.

“We’ll be there in about an hour, and then you’ll get a full check up, but right now I’d like to check on the egg to make sure nothing’s wrong with it. Is that okay?” Cas knew it was the wrong thing to ask because the siren scrambled to get as far away from Cas as quickly as he could manage, shaking his head and covering his stomach with an arm.

Cas put his hands up and waited until the siren had calmed down a little. “Okay, okay, I’ll leave your egg alone and I won’t go anywhere near it if you don’t want me to.” He got a vehement head shake and put his hands down in his lap. Cas waited until the siren’s breathing had evened out and started inching his way over to the other side of the van. The siren eyed him suspiciously but allowed him closer as long as he kept away from the egg.

The siren surprised Cas by shifting upwards and depositing his head in Cas’ lap and letting him run his fingers through his damp hair. A hiccup-y sob escaped and never before had Cas felt such pity for something he’d rescued. He tried imagining what the poor creature had been through; he’d probably been captured from the wild if Cas had to hazard a guess, beaten, starved, held captive by one of the cruelest men on the planet, pregnant, and now in the hands of total strangers he had to trust not to hurt him more.

Cas kept up a litany of sweet nothings as the siren cried himself out, and he eventually fell quiet as Gabriel pulled in at the back of the rescue center.

“You have to get back on the stretcher, now, okay?” Cas’ heart threatened to shatter when Freckles (that’s what Cas was calling the siren in his head until he had a name to work with) gave a pathetic whine of fear and shook his head. “I know, I know you don’t want to, but you’re hurt and we have to take care of you. You’ll have a big tank to swim around in, and once your egg has hatched, we can discuss the two of you going back out into the wild. If you want, I’ll be the only person you have to interact with. It’ll just be you and me and nobody else, okay?”

Freckles thought about it for a long time and gave a tiny nod Cas almost didn’t catch. He helped Cas get him back on the stretcher, but wouldn’t let Gabriel take the spot by his head. Cas shooed his brother off once they got Freckles on a gurney; he’d given his word it was just going to be him and damned if he was going to break it.

Cas could almost feel the fear radiating off Freckles as they traveled down the stark white hallway to what Charlie and Kevin called the Knockout Room, since it was where they put animals under. Their other siren was too well behaved to warrant trips to that particular room when it was time for his check ups, but Freckles was terrified and likely to lash out.

Freckles whimpered in fear when they came to a stop in the middle of the room and tears started welling up again. Cas looked up from where he was preparing the anesthetic and saw that Freckles had one hand white-knuckling the railing and the other clamped over his egg bump. The tears had finally spilt over and were creating little wet spots on either side of his head and the blatant fear and terror coming off him were like sucker punches to the gut.

“Hey, hey, hey, there’s no need for that now.” Cas said as he crouched down to Freckles’ eye level. “I know it’s scary, but everything’s gonna be okay. You trust me, right? So if I say it’s okay, then it’s okay.” Freckles was good after that until Cas came bearing the mask, at which point the tears came back and he started keening.

It took twenty minutes to get Freckles to hesitantly accept the mask over his mouth and nose, but only after Cas had sworn up and down that it wouldn’t hurt the egg. And it wouldn’t, since it had been specially made for sirens carrying eggs. The only drawback was that it was slow-acting, sometimes taking up to two minutes to put a siren under.

For the first breath or two, nothing happened, but then Freckles started getting drowsy and he turned wide, fearful eyes in Cas’ direction, like he didn’t understand what was happening.

“I know you’re getting sleepy, but don’t try to fight it.” Cas said, taking the fingers of the hand not holding the mask to Freckles’ face and running them through his hair. “Just go to sleep, and when you wake up we’ll get you something to eat, yeah? Something good for the egg?” Freckles nodded slowly, eyes already at half mast and falling quickly. They finally fluttered shut almost a minute later and Cas sighed when he lost consciousness.

The other siren in the facility had never been that bad when they still had to put him under for check ups, but then again it only took him about thirty seconds whereas Freckles had taken over two minutes.

Speaking of him, Cas had no idea how he was going to react to another siren. Of course they would have separate holding tanks in the back, but once Freckles was ready, he would eventually be let into the main tank, which is where Sam spent most of his time. Sam was aggressive towards other sirens (or at least the one other one they’d housed for a few weeks until it could be transferred to San Francisco), and he was very territorial over the workers he interacted with. There was no telling how he’d react to the sudden presence of a pregnant siren who needed more care and attention than he did.

Deciding to cross that bridge when he got there, Cas took Freckles to the ultrasound room to get a look at the egg. It kinda felt like he was breaking a promise, but it was for Freckles’ good. If the egg was broken or damaged they would need to remove it before his body tried to expel it on its own. Normally that wouldn’t be an issue, since as far as Cas knew sirens did it all the time, but Freckles was far too weak to survive something like that.

Cas turned the machine on and waited for it to warm up by warming some of the gel between his hands.

“Charlie!” he called, getting the attention of the redhead as she walked by

“Yeah? Whatcha need?” she asked.

“Pull up a stool. I need your help for two seconds.” Charlie complied and looked over the unconscious siren.

“This the one you rescued? Man, he is in rough shape.”

“Yeah, I know. Can you lift the towel over his stomach? Awesome.” Cas spread the thick gel over Freckles’ stomach, getting a feel for where the hard little lump was located. “Well, it feels fine so far, but I can’t say for certain yet.”

Charlie handed him the wand and he set to work running it slowly over Freckles’ bump.

“Is that it?” Charlie asked, squinting at a white spot on the screen about twice the size of a golf ball.

“Yeah, that’s it. It looks perfectly fine, so we probably won’t have to do emergency surgery to remove it. Judging from the size, I’d say he’s about one to two weeks along.”

“And how long do sirens stay pregnant for?”

“About a year. The first six months are devoted to the development of the fry and the last six are for stocking the egg yolk with the nutrients the fry will need to finish growing after the egg is laid. And then it takes almost a month for the egg to hatch.”

“Just out of curiosity, what’s the average brood size?”

“Sirens normally only have one fry at a time. Why?”

“Because yours is having twins.” Cas jerked around to look at the screen and saw that a second white spot identical to the first had joined the party.

“Hot damn.”

* * *

 

The rest of Freckles’ exam went without any real shocks. His weigh in and height check showed he was severely underweight for a siren his size, and especially so for one carrying two eggs. Trying to find a vein to draw blood from was a real bitch thanks to his skinniness, and what would be called a pelvic exam on a human revealed that Freckles had both male and female siren parts, which was how he was able to carry the eggs in the first place. They would have to wait for his bloodwork to come back to see if he had any diseases or start him on anything, but Cas already had Garth putting a diet together that would help him gain weight and give his body the astronomically high amounts of resources his body would allocate to the fry.

After everything was done, Cas donned a wetsuit and sat with Freckles in the shallow wading part of his tank where he would interact with his handlers (i.e. Cas) and waited for the anesthetic to wear off.

It took about an hour, and Freckles came back to consciousness just as slowly as he’d lost it. His efforts to wake up were full of little whines and whimpers that Cas found both adorable and sad at the same time. Cas gently stroked his hair through all of it, and his back on one occasion when he’d gotten sick.

Once he was awake enough to swim, Freckles wriggled away from Cas and swam down to the very bottom of the tank and curled up where nobody would be able to see him.


	2. Chapter 2

**Notes for the Chapter:**

> No dialogue this chapter...
> 
> Not sure how that happened ¯\\_(ツ)_/¯

Dean’s life sucked; he was aware of that and had been from the moment he’d hatched. For one thing, he’d hatched under the dark of the new moon, which was a bad omen among sirens. For another, he was mute, so he couldn’t sing with the rest of them or even speak to them. And if being a mute siren hatched during a new moon wasn’t bad enough, Dean also possessed a female siren’s nest, which allowed him to carry eggs.

From the time he’d hatched to the time he’d set out on his own, he’d been ridiculed and abused by the other members of his shoal, and that included his own father. He was probably the worst offender, since he and Dean were often in close quarters with no other witnesses. His mother would never have stood for it, but she had died laying Dean’s egg, and his father had always blamed Dean for that. The other shoal members were just as awful; his hunting partners would abandon him, the elders took almost everything he caught and basically left him to starve to death while they enjoyed his spoils, and everyone treated him like shit.

At some point had gotten tired of his shoal’s shit and set out on his own. Sirens didn’t normally live on their own, if times got hard there wasn’t a shoal to fall back on, but it could be done. So one night, Dean stole as much food as he could carry, and took off to find a reef for himself.

Things went to shit the instant he laid eyes on the tiny reef. Once there, he’d been netted by humans and they’d kept him in a tank, drugged to the gills. Most days he didn’t have the energy to move from the tank’s hard bottom, or to eat the meager meals they threw to him whenever they remembered Dean had to eat too. They kept him collared, his wrists and tail chained, but it didn’t make a difference since Dean couldn’t keep conscious for more than an hour at a time.

And then one day they put another siren in Dean’s tank. He had evil yellow eyes and a matching tail, and when he showed up Dean knew things were about to get worse. His name was Azazel, and one of his favorite activities was sticking his fingers into Dean’s slit, where he eventually found the entrance to Dean’s nest.

Dean didn’t like to think about the days following, the days he spent being violated by Azazel while humans had watched and urged him on. Dean could have cried in relief when Azazel was suddenly denied access into Dean’s nest and he got sick, meaning Azazel was moved out to prevent him from catching whatever Dean had. A few days later he felt something hard and round under his hand, meaning that the other siren had managed to fertilize an egg.

Dean knew the egg would probably never make it long enough to be laid; he was too thin to support one and getting thinner every day, so his body would eventually absorb the egg to use it as emergency resources. And even if by some miracle it did, he’d probably never see it again. Despite both those facts continually repeating in his head, Dean got attached to it.

He wanted desperately for it to live, to get to have the life he’d been denied. But he needed a saviour for that to happen, and they never came. Dean barely noticed when he was sold, barely noticed when his tank got even smaller, barely noticed when the meager meals stopped coming altogether. He was tempted to try and smash the egg himself so his body would go ahead get rid of it before it tried to keep the thing alive with resources he didn’t have, but he could never do that, not to the tiny life that was totally dependent on him for its survival. To kill it seemed like a breach of trust of the utmost degree. Then the miracle they both needed arrived.

He had dark hair and eyes the color of an ocean Dean couldn’t remember and he was there to rescue Dean. He panicked when the top of his tank was removed, something that signified bad things, but one look at his saviour and Dean quieted down.

It took two people, his dark-haired rescuer and some other, shorter guy that Dean wouldn’t trust to watch a mound of sand, to lift him out of the tank once his chains had been cut, and Dean was okay with that. What he wasn’t okay with was when the short one got too close to the tiny bump the egg was making. Dean panicked, hitting him in the face with his tail and pulling away as far as he could get.

They carried him out to a metal box and laid him out on its frigid floor. Dean’s saviour came with him, and covered him in wet cloths to keep him moist. He kept up a dialogue to Dean, even though he wouldn't get a response, and Dean found that he was okay with it. Normally Dean hated it when people talked to him like they weren’t expecting any answers, but this time was different.

Cas tried to be as gentle as possible as he broke the infernal metal cuffs open, the ones that cut into Dean’s skin and were two sizes too small. Dean especially hated the one around his neck; he’d often worried that someone would take it and move it just a few inches higher, over his gills, and suffocate him.

Surprisingly, Dean found himself warming up to the guy. That was until he asked about the egg. Cas checking on the egg meant Cas getting close to the egg and that was unacceptable. Saviour or not, he could still harm Dean’s egg and and Dean wasn’t willing to risk it. And Cas was so damn understanding and let Dean calm down before he tried approaching again. Suddenly, Dean had his head in Cas’ lap, sobbing hard.

He wasn’t sure why he’d even started crying in the first place; everything just seemed to chose that moment to hit him and it was too much for him to handle. That was also when he realized he was in the hands of total strangers and that they now controlled his life. If they wanted to get rid of the egg, or take it away once he laid it, or force him to keep laying eggs, Dean didn’t get a say and that’s what would happen.

Dean desperately wanted nothing more than to keep his egg and see it grow up, so when Cas asked him to get back on the stretcher, he whined in fear. Getting back on meant submitting to ‘them’, giving them access to do whatever they wanted, and that was the last thing Dean wanted.

And then damn Cas, with his soothing voice and reasonableness managed to coax him inside the building, and Dean hoped that he’d at least get to see the fry once. Cas had Dean on some sort of table with wheels, and Dean had no idea where they were going, but Cas kept a thumb rubbing his head, so it was kind of okay.

Dean froze in panic when they reached their destination. The room itself didn’t stand out all that much, but it smelled like the drugs the humans had given Dean, the kind that kept him docile and unresponsive and made him sick when they wore off. Cas was going to give him more and take the egg away and Dean didn’t want that.

Cas noticed that he was panicking and did his best to calm Dean down, but never did he once assure that he wouldn’t touch the egg. Yeah, he’d already said as much when Dean had freaked out the first time, but of course Dean hadn’t believed him. He had no reason to tell Dean the truth; sure he’d rescued Dean, gotten him out of hell, but Cas was his own person with his own motives.

But Cas was so reassuring, and Dean wanted to believe him, but Dean’s already warring emotions fought harder with each other when Cas came back carrying a mask like the one the other humans had held over his face after they’d netted him, and suddenly Dean was back there, caught up in a net and too weak from hunger to struggle.

It took a long while to grasp that someone was talking to him, someone with a voice like they’d swallowed gravel and sand. It was Cas, telling him that it was okay, that it wouldn’t hurt the egg. Cas wouldn’t worry about harming it if he was planning on killing it, right? Dean decided that, no, he wouldn’t, but he made Cas swear multiple times that the egg wouldn’t get hurt.

Cold fear clawed at his insides when Cas first put the mask over his face and Dean got a mouthful of cold, bitter gas. Nothing happened for a second or two, but then a wave of drowsiness hit Dean, as did the realization that it was really happening. That he couldn’t back out.

Dean turned his head to Cas, just to get one last assurance that the egg would be fine. The world was starting to blur out, and Dean barely caught what Cas was saying; something good for the egg? Dean nodded, which sapped almost all of his draining energy, and passed out to the world dimming and Cas running a hand through his hair.

Dean wasn’t sure how long he stayed asleep, but it seemed like just minutes later that consciousness tickled at the very edge of his awareness. Dean struggled to wake up, but the drugs were still trying valiantly to pull him back under. Dean kept fighting, though, and little by little gained more ground.

He gradually became aware of his surroundings, like the fact he was sitting in saltwater, his top half in Castiel’s lap. Cas was supporting his head with a hand and absentmindedly rubbing his thumb back and forth. He then was aware that he was about two seconds away from expelling his pitiful stomach contents, and Cas did too. A bucket appeared in front of his face and Cas rubbed his back as his muscles painfully contracted and he threw up bile.

Dean was then aware that the egg was in a different position. Before, it had been sitting vertically, but now it felt like it was sideways, one end pushing against his skin and the other poking his liver. A sharp pang of betrayal clawed at his heart, because Cas had said he wouldn’t touch Dean’s egg without permission, and Dean could feel the proof he’d gone back on his word.

The tears stinging his eyes were washed away by the water as Dean wriggled out of Castiel’s grasp and swam down to sob where no one could hear him.

**Notes for the Chapter:**

> There's definitely Sam next chapter, so that's something to look forward to.


	3. Chapter 3

**Notes for the Chapter:**

> This is going up a little early, so enjoy!

“How is he doing?” Cas jumped at Charlie’s voice, putting a hand on the metal railing in front of him to steady himself.

“Honestly? Not good. He’s eating everything we’re giving him, but he won’t come up from the bottom of the tank and he hasn’t shown any interest in the live prey we’ve put in there. I don’t know what to do.”

“Maybe we should introduce Sam.” Charlie suggested.

“No, Sam’s reaction would be too unpredictable; remember how he reacted to the other siren we housed?”

“Yeah, maybe not a good idea. He might just need time, you know?”

“Charlie, he’s been here for over a week. If there isn’t any improvement on his part we’re going to have to step in and move him to the special care unit, and I don’t think that would help.”

“Worst case scenario?”

“He’s lost the will to live and we’ll have to put him down.”

* * *

 

Sam smiled as the small human child on the other side of the glass laughed as his tail came up and destroyed the fragile bubble ring. She waved goodbye as she followed after her mother and Sam found himself wishing for one of his own. He knew that it wouldn’t happen as long as he stayed, but the thought of going back out into the open ocean terrified him, and not even the idea of a mate and fry could make him go back.

With the viewing room empty, Sam was free to hunt for prey, namely the crustaceans and schooling fish that Cas bred just for him. Used to be he could get food whenever he wanted, but people started complaining about the blood and overall mess that accompanied him feeding, so Cas had set aside blocks of time specifically for him to eat. The clock on the wall said it wasn’t quite time yet, but with it being the middle of the week Sam knew it was unlikely they were going to get many more visitors before closing.

Sam slowly circled the tank, trying to spot where the spiny lobsters were hiding amongst the rocks of the reef, and knowing they would be a waste of time before nightfall. As he passed by the barred gates leading to the holding tanks in back his gills picked up the sweetest, most tempting scent, and he paused in front of the closed gate. Right away, Sam knew that such a tempting scent could only belong to his mate and pushed on the gate, surprised when it didn’t open.

He scowled at the metal bars, but he could definitely smell his mate on the other side. Now that he was closer to the source, Sam noticed his mate’s scent was off. Something wasn’t right; perhaps his mate was ill or injured?

No matter which way he craned his head, Sam couldn’t get a look through the gate’s bars, but his tank was right next to the one his mate was in, and so he’d be able to get a better look. At first Sam didn’t see anyone; the tank was just as empty as it had been before and since Lucifer had inhabited it, and Sam was confused. He soon found his mate, but it wasn’t anything like Sam had been expecting.

He was curled up at the bottom of the tank, as far into the corner as he could get himself. He was pitifully thin and was as pale as the sun-bleached bones that littered Sam’s native reef, despite the fact he should have grown up under the sun. His neck, wrists, and the end of his tail were ringed with rough scar tissue, bruises of varying ages covered his skin, and if it weren’t for the fluttering of his gills, Sam would have thought his mate was dead. Sam wanted nothing more than to rush over and hold his mate (and to gut the people who had dared harm him), but the best he could do was swim to the bottom of his tank and put his hands on the glass keeping them apart.

Up close, Sam could see that despite his mate’s injuries, he was still beautiful. His tail was the most magnificent green he’d ever seen, and his eyes were probably the same color. His gold-blonde hair rivaled his father’s vast collection of treasures, and Gods, did he have the face of one. Pink, pouty lips, cheekbones carved from the purest of stone, and freckles everywhere.

Sam noticed Cas and Charlie on the metal catwalk that crossed over the back tanks, and that they were in the middle of a serious conversation. They kept shooting glances down at his mate, and Sam felt a surge of anger for them discussing his mate without him present.

Casting one last look at his sleeping mate, Sam swam to the wading ledge at the top of the tank where he could stick his head out and hopefully catch part of what they were saying. They were a little hard to hear over the pump system, but Sam managed to catch the last little bit of their conversation and it made his blood boil.

“-and we’ll have to put him down.” The thought of Cas, anyone, putting his mate down like a rabid animal had Sam seeing red, the fins on either side of his head flaring out and his tail lashing the water. If it weren’t for the divider between the two tanks with its tall fence, Sam would go and guard his mate until his last breath. For the moment, Sam had to make do with keeping a constant vigil.

* * *

 

On top of worrying for Freckles, Cas noticed Sam was refusing to leave his tank. Cas hoped he wasn’t sick or something; when that happened, Sam removed himself from the main tank and sulked around in his back tank until someone noticed. He seemed incapable of simply telling someone he didn’t feel well, but that was Sam.

Cas noticed that he was also favoring the right side of his tank, which was the divider between him and Freckles, and shooting death glares at Cas when he thought they wouldn’t get noticed. If Cas looked at Sam’s behaviour like he would for any of their other animals, Sam was pissed about the new addition and that he couldn’t do anything about it. But sirens were equal with humans when it came to their reasoning and response behaviours, meaning that it was never that simple.

It had been going on for three or four days, and Cas was starting to get complaints from people who wanted to see Sam, but couldn’t since he wouldn’t come out. Normally Cas tried to not interfere with Sam’s life or dictate where or how he spent his time, but it was beginning to border on ridiculous. Sam was barely leaving his tank to get food, and Cas didn’t want a repeat of the last time time Sam had stopped eating.

Cas put on his wetsuit and stepped onto the wading ledge of Sam’s tank. At that moment, Sam was pacing the divider between him and Freckles and trying to get a look at the other siren where he’d hidden himself in a patch of kelp. He whistled loudly to get Sam’s attention and sat down to wait for Sam to come to him. Sam didn’t take well to orders or commands, and it was best to let him do things on his own time.

Sam’s head broke the surface a moment later and he pulled himself up onto the ledge next to Cas. His gills closed up on contact with the air and Sam barely waited long enough for his auxiliary lungs to kick in to start questioning Cas.

“Where is he, Cas? You haven’t done something to him, have you?” Cas did a double take at the protective growl in Sam’s voice and thanked anonymous higher powers Sam wasn’t a venomous siren, because the cartilage spines of the fins on Sam’s hips had spread and were digging into Castiel’s leg.

“No, I haven’t done anything to him. He’s in the kelp patch right now. Why do you care so much about him, anyway? You’ve never met him.” Sam looked away; he couldn’t tell Cas they were mates, he wouldn’t understand.

“What’s wrong with him?” Cas noticed the obvious deflection immediately, but decided to let it slide.

“We rescued him from a smuggler, and he’s been like this ever since we brought him here. We’re moving him to the special care unit tomorrow because he won’t come up from down there and we have two eggs to think about in addition to him.”

“What! He’s pregnant and you just left him alone?! It’s no wonder he’s being like this! Cas you just can’t do that!” Sam’s fins flared out at Cas’ stupidity; his mate was carrying eggs and Cas had just thrown him into a tank by himself?!

Sam knew Cas had just been doing what he thought was the right thing, but he’d not only put his mate’s life in jeopardy, he’d also put the lives of his mate’s fry at risk too. Sirens carrying eggs had to be taken care of, otherwise they’d get upset and depressed and would eventually lose the will to live. It wasn’t that they were weak, the eggs took a lot out of them and the urge to protect them overrode everything else. They were extremely vulnerable until the eggs were laid and whole schools would protect them with their lives if necessary.

“Sam, calm down.” Cas’ voice barely registered over the rage at his actions and the knowledge that special care was one step away from euthanization.

Sam felt a sharp scratch against his neck and his hand flew up to cover the spot. A wave of vertigo hit him and Sam couldn’t keep himself upright anymore. He sagged against Cas, and a whine escaped him as his vision started blurring.

“I know, Sam, I’m sorry.” Cas said as Sam started losing consciousness. He’d halfway expected Sam to get aggressive, albeit for slightly different reasons, and had brought a sedative along in case he’d needed it. He knew Sam hated them because they didn’t work right away, but the syringe had been the easiest thing to conceal.

Sam completely lost the ability to hold himself up and soon thereafter lost consciousness, too.

**Notes for the Chapter:**

> Next week sees Sam and Dean meet, so there's that.


	4. Chapter 4

Sam came to curled up in the isolation tank. Cas had showed it to Sam when he’d first arrived; it was designed to hold troublesome animals (or a siren), and it was just big enough for Sam. It wasn’t quite long enough for him to stretch all the way out, but Sam was big for a siren and whoever had designed it had had more average-size sirens in mind.

When Sam had first arrived, Cas had explained what it was, and that it was mandatory for anywhere that would be keeping sirens. The bottom was secured to the floor so it couldn’t be knocked over, and the top was super heavy so it couldn’t be pushed off. Which meant that Sam was screwed if he wanted out.

Sam had never been in it, but he’d come close the first time they had let Lucifer into the big main tank. The only reason it was Lucifer who’d gotten put in it and not Sam was because Lucifer had started it, though they’d both ended the day with injuries bad enough to warrant a visit to Kevin, the little shrimp of a human who was the best at sewing stitches.

Sam slumped against the side and wondered why Cas had seen it necessary to put him in isolation. He hadn’t gotten violent with Cas; just yelled a little at his complete and utter stupidity. And then it clicked that Cas had moved him because he didn’t want Sam to see them move Dean out of his tank because he was probably afraid Sam would throw himself at the glass or hurt himself trying to stop them.

Sam threw himself up against the tank’s heavy top, but it wouldn’t budge. If he was still in the isolation tank, that meant they hadn’t moved his mate yet and he still had time to stop them. But first he had to get out.

* * *

 Dean didn’t really remember what happened after he left Cas. There hadn’t been a lot of variation to the days following, so it wasn’t surprising when they all started bleeding together. Food came and Dean ate it, if not for himself, then for the egg that needed it more. They managed to get most of Dean’s favorite foods, but it wasn’t as good as fresh. And even though they’d put live prey in the tank, it didn’t even really matter, since the egg was making him sick again.

It had backed off when Dean had been starved and dehydrated, but now that he was in a tank with fresh water and a food supply, it had returned worse than the first time. Lethargy and a constant, roiling nausea meant Dean could only do one thing and that was lay at the bottom of the tank. At least there was a kelp patch, so it kind of felt like home.

He vaguely remembered seeing another siren, this one with a flaming red tail, but Dean tried to ignore him as much as possible in the hopes he’d go away. It must have worked because Dean wasn’t really sure when the last time he’d seen him had been.

Dean woke up and could instantly tell something was going on because there were a couple of people milling around at the top of his tank. He couldn’t tell what they were doing, but he was pretty sure he wasn’t going to like it.

Dean hid in the kelp patch, his tail darkening in patches to help camouflage him better. He hoped that they wouldn’t see him, but Dean knew better than to hope for such things. Dean’s head snapped up at a disturbance in the water and terror seized his gut at the sight of two humans in black diving gear with a net held between them.

* * *

Sam threw himself up against the tank’s lid once more and it budged just a little. Sam had about six inches of space between the tank and lid, but it wasn’t enough for Sam to squeeze through. Sam took a minute to catch his breath before he tried again. His shoulders were bruised and aching from him slamming them into the heavy, metal top and Sam was pretty sure he’d refractured one of his scapulas. Charlie was going to be pissed.

Two more attempts and Sam was triumphant, his reward about a foot of space that was plenty big for him to fit through. He landed with a wet thump on the cold, concrete floor, slinging water everywhere.

Sam didn’t waste any time and set off for the tanks, using his hands to pull himself forward and his tail to push. Soon his skin had dried out and was chafing against the concrete, but Sam didn't pay any attention to it. His mate needed him, and Sam didn’t have any time to waste.

Thankfully Sam didn’t run into anybody on his way there, or he would have been stopped. By the time Sam reached the tanks, his tail was leaving behind blood smears from the scales being forcefully yanked out and the delicate skin underneath torn open.

As opposed to the time Sam had had to be moved to special care, there was just one person standing watch over the tank. Cas paced back and forth as he watched the divers try and corner Freckles. It wasn’t working out too well, since Freckles was trying his damndest to not get caught and he could still swim faster than the divers even with his emaciated state.

Cas didn’t enjoy doing this to Freckles, it felt like he was betraying the siren’s fragile trust in him, but it was for his own good. They could better care for Freckles and his eggs if there wasn’t forty feet of water between him and the trained medical professionals.

A look back down into the tank showed that the divers finally had Freckles cornered and a look behind him as something crashed to the floor showed Sam pulling himself forward seal-walk style. Blood was smeared on the floor in a trail behind him that Cas knew had to stretch all the way back to the isolation tank.

“Sam?” Cas said, “What in the hell are you-” Sam didn’t give him a chance to finish his question as he threw himself forward the last few feet and into his mate’s tank. The salt water stung his open wounds, but the pain flew from his mind when he saw his mate pressed into the corner, desperately trying to get away from two divers and the net strung between them.

His mate’s tail had faded into a dark olive green with startling bright blue rings, meaning each of his spines was topped with a sharp point capable of delivering a potent venom. As Sam quickly closed the distance between them, he noticed the pure terror written all over the other siren’s face and body language.

All his fins were spread out wide, displaying more of the blue rings and making him look bigger and more difficult to eat. He was backed as far into the corner as he could get, arms crossed protectively over the eggs in his belly, and the closer Sam got the more clogged the water got with nasty fear scent.

Sam put on a burst of speed and threw himself between his mate and the divers, flaring his fins and growling low in his throat. The divers paused, and it gave Sam an opportunity to glance down at his mate. Sam could tell he wasn’t really registering what was going on around him, damn near on the verge of hyperventilating, whining and keening with every other breath.

As a last-ditch effort, Sam brandished the blade-like spines on either side of his tail, the ones that Cas likened to those of a surgeon tang. They’d been essential for survival on Sam’s reef, since almost everything there could and would kill a siren, including the other sirens. They were more than sharp enough to slice through the net in front of him, and were definitely more than enough to clip a human’s jugular.

Suddenly the divers jerked their heads up and turned to leave. Sam made sure they were totally out of the tank before he dropped his guard and turned to his mate. Tears in the form of tiny bubbles clung to the corners of his eyes, which were glassy and unfocused. He didn’t react when Sam lowered himself down to his mate’s eye level, and Sam took it to mean he was caught up in a memory of the past. Cas had said his mate had been rescued from a smuggler, so perhaps he had been caught by divers with a net.

Sam gathered up his trembling mate, extremely careful of the sharp spines, and sat down with his back pressed against the glass. He settled his mate in his lap and pulled his head down to rest in the crook where Sam’s neck met his shoulder so he could scent. His gills fluttered frantically against Sam’s skin, struggling to pull oxygen from the water around them.

“Shh, little one, it’s okay.” Sam soothed as he tried to get his mate to calm down, “It’s alright, just breathe.” Sam kept up a litany of reassurances and a hand rubbing circles on his mate’s neck until he stopped shaking. Eventually the whining stopped and the tears decreased in amount, but not for one minute did Sam think his mate had let his guard down. There was still a distrustful tension in his shoulders, and while the venomous spines had been sheathed, his tail hadn’t faded back to its normal emerald, which Sam knew to take as a reminder that he was still very dangerous.

“Are you back with me, little one?” Sam asked. His mate made a token struggle to get away when he heard Sam’s voice, but he was exhausted and the hands at his waist and the back of his head were stronger than him, and he eventually gave up. “It’s alright, I’m not going to hurt you.”

Sam got a wave of a tail in return and then his mate was struggling again. Sam felt the muscles under his hand contract and before he could ask what was wrong, there was a strangled whine from the emaciated siren in his lap followed by the acidic scent of vomit.

“Are the eggs making you sick?” Sam asked. The other siren gave a tiny nod that Sam felt more than saw. “That’s okay, I’m sure Cas can give you something to make that go away.” When Sam didn’t get a response, he looked down to see that his mate had fallen asleep.

Patches of brilliant green bled through the olive and blue on his tail as he relaxed in sleep, and his shoulders lost their tense hold. Sam knew that he couldn’t be more that thirty cycles old, but sitting in Sam’s lap, he looked barely old enough to venture past the reef. Only the scars from a life of experience belied his age.

“Gods, little one, you’re perfect and...and I don’t even know your name.”

**Notes for the Chapter:**

> I won't be updating next week because next week is Christmas, but I will update the Friday after that. 
> 
> Comments always leave me grinning like an idiot, so comment to make a problematic neither happy :D


	5. Chapter 5

**Notes for the Chapter:**

> Look, a chapter no one has ever seen before!

Food for his mate came sometime later in a box with holes in it to allow it to sink. Sam hated to wake up his mate when it was obvious he needed the rest, but he needed the food more if he wanted to keep the eggs.

“Wake up, little one, you have to eat.” Sam said, rubbing his mate’s arm to try and wake him up. His mate tensed up when he realized where he was and whined low in his throat, curling in on his belly. It broke Sam’s heart that his mate was afraid of him, but he probably had a legitimate reason to fear an unknown siren. If Sam had to guess, that was who had fertilized the eggs he was carrying.

“Shh, it’s just me. I know that might not mean much, but it’s okay.” The siren in his lap relaxed marginally, but not much.

“Y’know, I haven’t heard a single word out of you, yet, and as much as I like calling you little one, I think I’d like your name name better.” Plus, Sam thought, it would be better than thinking of him as ‘his mate’ all the time.

Sam was surprised when he got a head shake in return instead of a name, and he hefted the other siren up so they were eye to eye. “Can you not talk, little one?”

The other siren dropped his gaze and shook his head as a fierce blush crept up his neck.

“You’re mute?” The instant the words left his mouth, Sam knew he’d said the wrong thing. He hadn’t meant to, but it had come out sounding incredulous, like a mute siren was weird, something to be mocked and shamed. Tears bubbled up in his mate’s eyes, followed by a sniffle that quickly turned to sobs. Sam turned his mate so that he was facing Sam and put a hand to the back of his head while the other rubbed circles on his back.

“No, no, don’t cry, shh.” Sam soothed, dropping his head to press his lips into his mate’s hair, “I’m sorry, I shouldn’t have asked that. Please stop crying, little one, please.” Sam grew more worried as the hiccuping sobs continued, but after a few minutes they subsided.

“That’s it; Gods, I’m really screwing everything up, aren’t I?” That elicited a tiny huff of laughter, so he probably wasn’t doing too badly. “I’m Sam, by the way. I know you can’t tell me your name, but maybe you can mouth it; I’m pretty good at reading lips.” It was a talent he’d perfected from watching people talk through glass day in and day out, so it wouldn’t be that hard.

Sam felt his mate’s lips moving against his shoulder, and he laughed.

“This can only work if I can see your lips, you know.” Sam murmured, and his mate pulled back. He wouldn’t look Sam in the face, but Sam still caught what he was trying to say. “Dean? Is that your name?”

Dean gave a shy nod, and dropped his gaze even further.

“Dean...I like it.” Sam looked over to where the food was and remembered why he’d woken Dean up in the first place. “You need to eat, Dean.” Dean looked up at him, and before he could do anything, Sam held him tighter and swam closer to the food and away from the nasty vomit scent.

Dean paled and turned green around the gills when Sam opened the container of food, and turned his head away when Sam offered some sea urchin meat.

“Please, Dean, your eggs need this.” Sam knew it was a low blow, bringing the eggs into it when Dean looked about ten seconds from throwing up again, but he wasn’t wrong. After a long moment of consideration, Dean reluctantly opened his mouth and allowed Sam to feed him the piece of urchin meat. He had difficulty swallowing it, but he eventually got it to stay down.

They stayed like that for a while, Sam hand-feeding Dean clams, mussels, bits of kelp, and pieces of urchin, until everything was gone.

“You did so good, Dean, eating everything.” Dean’s stomach gave a treacherous rumble, and then Dean was up and across the tank, leaning over a rock structure as he vomited up everything he’d just eaten. Most of it hadn’t gotten the chance to even begin to be digested, which meant it had to _hurt_ coming back up.

The closest Sam had ever come to a pregnant siren was the one time Crowley had gotten a female to stay at the bone reef for more than a week, but she’d thrown herself against the rocks to kill it and left as fast as she could after leaving behind a bloody mess of egg materials. Sure there had been other females living there, Ruby, Lilith, Meg, but they were in a big threesome together, so no eggs would ever come of their union. But even Sam, with his limited knowledge and inexperience, knew that the symptoms Dean was showing weren’t healthy.

Sam swam over and rubbed Dean’s back until the forceful heaves subsided, and pulled the trembling siren back into his lap. Dean went without complaint, too exhausted to struggle, and quickly fell asleep again.

Sam bit his bottom lip in worry as he looked at Dean, knowing that he couldn’t keep going like that for much longer. He knew he should go to Cas, but he also knew that Dean probably didn’t trust the human and wanted to maintain some form of autonomy. Sam compromised with himself, and decided that if he couldn’t convince Dean to see Cas in five days, then he would go himself.


	6. Chapter 6

**Notes for the Chapter:**

> Due to an unforeseeable string of events beginning with a sore throat from Hell itself and eventually ending with my own inability to actually do thing needing to be done, I haven't updated in almost four weeks. Words cannot properly capture how sorry I am, so here's a chapter.
> 
> On that note, the end is so fluffy I could almost feel the cavities forming.

Dean woke to Sam rubbing his back, and he wasn't sure if it was a good thing or not that he didn't flinch. In Dean's defense, it was hard to be afraid of Sam when he was so gentle, never raising his voice or treating Dean like he was a burden.

Dean gave a sleepy whine as he nuzzled further into the sand, but Sam was persistent. Dean wished Sam would go away; he'd already had (and thrown up) breakfast, and it didn't feel like time for lunch, a fact Dean was grateful for. It hurt to throw up, and as much as he wanted his egg to live, he almost wished it would die and was tempted to throw himself against the rocks and kill it himself.

Dean hated himself whenever that thought reared its ugly head, since he should have been trying to do everything in his power to ensure its survival. But the reality was that Dean was too thin to support an egg and if something didn't change soon, his body would make the decision of who got to live for him.

"Can you get up, Dean?" Sam asked, "Please?" Dean knew what Sam wanted and had wanted for the past few days, for him to go see Cas, and he was close to giving in. As much as the human unsettled him, he was the most likely to know how to help. Dean reluctantly sat up and met Sam's worried hazel eyes. They didn't match his vibrant red tail, which was odd, but Dean thought it gave him character.

"Will you please go see Cas today? You've started throwing up blood, and you're getting worse instead of better, and- and I'm worried about you, little one." He knew that Sam meant he was worried about him dying, which was an outcome he could see happening. As much as it hurt to think about, Dean would eventually be okay if the egg didn't make it. He'd move on and maybe at some point find a mate and have another to replace it. But if he died, then that was it for both of them, and neither would ever get another chance.

So Dean shyly nodded and dug his nails into Sam's back as he scooped him up and swam to the surface. Cas was already there, kneeling in the water and wearing his wetsuit. There was a metal cart behind him, but Dean chose to ignore it and instead focused on the little ripples Cas was making in the water.

"Dean, can you look at me?" Cas asked. Dean didn't move, but raised his eyes to meet Cas' at Sam's gentle prodding. "There, that's better. Now, Sam’s told me that you've been getting sick after you eat, and that yesterday there was blood." Dean nodded, a little miffed that Sam had talked to Cas behind his back. But in Sam’s defence, there wasn’t much else he could have done. 

“I’m just going to do a little check up and see what we’re dealing with. Nothing major I have to put you under for, okay?” Cas reached behind him and picked up a slim metal thing that lit up at one end when Cas clicked it.

"Can you open your mouth for me? Great." Cas shone the light down his throat, hmm-ing to himself and tilting Dean's head back to get a better angle. Dean glanced to Sam and got a reassuring back rub, which helped the mounting panic a little.

Cas clicked off his light, and Dean pulled back into the relative safety of Sam's arms.

"From what I can understand, you've been throwing up a lot of undigested food, and that coupled with the repeated exposure to stomach acid has torn the esophagus. That's where the blood is coming from, and it should heal given enough time." Cas said, putting the penlight back on the cart.

To say he'd been shocked when Sam had come to him, beseeching help for Dean, was an understatement. From the way he was talking, Cas was afraid Dean was going to drop dead at any moment. Sam had said Dean was in bad shape, and Cas hadn't wanted to believe him, but the proof was right before his eyes. Dean was even thinner than the first time he'd seen him, and Dean had to have lost another ten pounds at least. Cas could count the knobs of Dean’s spine and his ribs were prominent enough to suffice as a xylophone. The egg bump was even more pronounced than before, and Cas knew they'd by the death of Dean before anything else.

"I have something I can give you for the nausea, to give your throat time to heal, that I'll put in your food, but I'd like to give you the first dose through an IV, and that way you can eat your next meal and keep it down." Dean shook his head and pressed himself further into Sam's lap as soon as the words were out, his eyebrows scrunched together in fear and distrust. 

"I know you don't want to, little one, but you might die if he doesn't. He's done this to me before, so I can say it's perfectly safe." Sam said. Cas knew immediately what Sam was talking about, and the words 'perfectly safe' weren't even anywhere close to how he would have described it.

Sam had gotten an IV exactly once, and it had been just before the siren before Dean had left. Sam and him hadn't gotten along at all, and they fought whenever they were in the same tank together. And even when they weren’t, they angrily paced the length of whatever it was separating them, be it the glass between the holding tanks or the gates from them to the main tank. Sam had suddenly stopped eating, and an IV had been necessary to give him back the nutrients he’d lost. Sam fought that too, as well as anyone who tried to touch him or get near him, and Cas had damn near lost him. 

Cas waited patiently as Dean pondered over the request; he desperately wanted to say no, but Sam's word clearly carried a lot of weight.

To Cas’ complete and utter shock, Dean nodded meekly. He then promptly buried his face in the crook of Sam’s neck, and Cas had to restrain his ‘awww’ when Sam brought a hand up to the back of Dean’s neck and dropped his head to whisper into Dean’s ear. He couldn’t hear what was being said, but Sam’s body language and Dean's terrified expression, reminiscent of the one he'd worn when Cas had put him under, said that he was trying to comfort the other siren. It was tooth-rottingly adorable, and a side of Sam Cas had never seen before.

He gave them a minute to themselves as he got up to get the IV and Cas’ heart clenched at the sight of Dean shaking in Sam’s lap. Sam had him cradled close, and his hands had once again strayed down to protect the egg bump. 

It was pathetic, almost, how afraid Dean was of things he wasn’t sure about, and while no one had ever observed a wild siren shoal for longer than it took to take a few blurry photos, Cas was almost positive they could be just as abusive and toxic as some human homes. Both Sam and Dean bore some of the same markers human children from abusive homes did, albeit in different ways. Sam had been aggressive, angrily pacing his tank and lashing out in panic at anyone who came to close. (Leaving several people, Cas included, with scars.) Dean, on the other hand, shrank away in fear, only trying to defend himself when he was backed into a corner with nowhere else to go.

Cas crouched down in the water and Sam carefully shuffled over. Dean’s head jerked up when Cas took his wrist, eyes wide, and he watched Cas like a hawk as he tied the band around his arm. Sam knew the protocol, so he held Dean’s head down in the crook of his neck so Dean couldn’t see what was happening.

“It’s best if you don’t look, little one.” he said, nodding at Cas to go ahead. Dean cried out when Cas stuck the needle in, and tried to yank his arm back, but Cas had the superior strength and grip of the two of them.

Cas let Dean have his arm back after he got the line going and the siren retreated back into Sam’s arms, glaring at him like he’d committed a capital offense. He rubbed at the site where the needle went in and whined questioningly at Sam, who huffed out a laugh.

“I know, little one, they’re not much fun. We can go back as soon as you’re finished.” he said, “And I mean when Cas says you’re finished and not when you decide you are.” Dean turned his puppy eyes to Cas, and he had to hold back a laugh. His were far deadlier than Sam’s, and heaven help them all if they ever teamed up.

“That’s not going to help anything, Dean, but I have one thing that might help pass the time. Would you like to see your eggs?” Dean could feel his eyebrows shooting up to his hairline, and he looked from his belly back to Cas with an astonished expression on his face. How in the world could Cas see inside him?

“Here, lay up on the concrete and I’ll show you.” Reluctantly Dean shuffled over to the edge of the concrete floor and pulled himself up onto it. He laid flat at Cas’ instruction and watched him as he moved the cart closer. 

“This,” he said, nodding at the equipment taking up the bottom space, “is an ultrasound machine. I use it on some of the larger animals we house to see what’s going on inside them, and if any of them are pregnant, I can use it to look at the baby. If the egg shells aren’t still too thick, which I don’t think they are, we can see the fry inside on the screen.” Cas looked away for a moment, as if guilty of something. “But I’ll need to get close to your belly. And we both remember how well that went the last time I asked.” 

Dean wrinkled his nose at the memory of him freaking out and absentmindedly rubbed the firm curve of his belly for a moment before nodding an affirmative at Cas to go ahead.

“Okay, then this will be cold.” Before Dean could ask what he meant, something wet and  _ cold  _ landed on his belly. He yelped at the frigid contact and scowled at Cas, trying to look as pissed off as he felt. 

“I know; apparently you can’t get used to that.” Cas said as he fiddled with his machine. Suddenly there was a pressure on Dean’s belly, but he didn’t get any time to question it as what had previously been inky darkness on the screen was replaced by a fuzzy black and white image. It and the pressure on Dean’s belly moved in tandem until the image settled on a light gray oval-y shape. It was a little bit smaller than Dean’s hand and there was a dark shape inside that vaguely resembled a -

Oh.

_ Oh. _

Dean didn’t really listen to Cas as he pointed things out, too mesmerized the image of his fry. Its body was tiny, but its head was disproportionately large, and one of its hands was tucked up by its head. As Dean watched, it wriggled around as if trying to get more comfortable inside its egg. Any lingering thoughts Dean had about killing the egg disappeared as he watched the tiny life inside him move and shift.

“Dean? Are you listening to me? I said it looks perfectly normal for this stage of pregnancy. It’s about nine to ten inches long right now, and you can see the yolk.” Cas said, “Now where’s...oh, there it is.” And then the image was moving to encompass another shape identical to the first.

For the first time, it clicked in Dean’s head that he was having twins. It should have clicked when Cas kept using plurals to refer to his fry, but Dean hadn’t been paying enough attention. The look of absolute shock on his face must have been funny, because Cas chuckled.

“Yes, you’re having twins, Dean. It’s certainly not what you expected, I’m sure.” Dean shook his head, unable to tear his eyes away from the two tiny forms on the screen. The second one was a little smaller than the first, but Dean didn’t pay it any mind.

“Hey, Dean, do you see those two little fluttery places? Those are their hearts.” Dean looked at Cas in astonishment, his fry were alive and their hearts were beating. “Actually, you might be able to hear them…”

And then there was a steady  _ thumpthumpthump _ , in time with the fluttering of the fry’s hearts, and Dean could feel the tears pricking at his eyes. It was kinda muffled from having to go through an egg shell and then Dean’s belly, but it was there and it was strong. They were still stubbornly hanging on despite all the shit Dean had (albeit involuntarily) put them through

Dean could’ve watched his fry forever, and he tried to, laying there long after the IV had finished and his tail had gone dry. Sam seemed just as enthralled with the fry as Dean was, peering at them with the awe and wonder of a youngling seeing the ocean outside the nest for the first time.

Eventually, though, Castiel had to put his equipment away and Dean was left to wriggle back into the water and swim back down to the nest he’d built from sand and kelp. The medicine Cas had given him had completely eradicated the nausea that had been his constant companion, and for the first time ever, Dean felt like things were going to be okay.

**Notes for the Chapter:**

> Comments make me so happy I can't even tell you. They also provide much needed sustenance that I will need for the upcoming winter months.

**Author's Note:**

> Comments and kudos are greatly appreciated. :D


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